2021/06/02 by Yi Chen, Muamer Kadic, Martin Wegener · 1 voice · 9 citations
Engineering · Physics and Astronomy · #Acoustic Wave Phenomena Research #Aerodynamics and Acoustics in Jet Flows #Quantum, superfluid, helium dynamics
paper · pdf · doi:10.1038/s41467-021-23574-2
openalex publication_date 2021/06/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Roton dispersion relations have been restricted to correlated quantum systems at low temperatures, such as liquid Helium-4, thin films of Helium-3, and Bose-Einstein condensates. This unusual kind of dispersion relation provides broadband acoustical backward waves, connected to energy flow vortices due to a "return flow", in the words of Feynman, and three different coexisting acoustical modes with the same polarization at one frequency. By building mechanisms into the unit cells of artificial materials, metamaterials allow for molding the flow of waves. So far, researchers have exploited mechanisms based on various types of local resonances, Bragg resonances, spatial and temporal symmetry breaking, topology, and nonlinearities. Here, we introduce beyond-nearest-neighbor interactions as a mechanism in elastic and airborne acoustical metamaterials. For a third-nearest-neighbor interaction that is sufficiently strong compared to the nearest-neighbor interaction, this mechanism allows us to engineer roton-like acoustical dispersion relations under ambient conditions.